oil pump

Ive run a high volume pump for around 20,000 miles, never once had a problem with pressure being too high or low.

Ive been through 3 sets of gears in that time. First set lasted about 5,000 miles because of a worn distributor. Second set lasted 200 miles because I beat on it out of the box. Last set has lasted about 15,000 miles after proper 500 mile break-in of the gears. All running 10w-30 snythetic. Never once had a problem with the pump drive shaft.

I plastigauged all of my bearing surfaces too so I was running slightly on the loose end of the factory clearances.

Car was used for drag racing, autocross, and daily driving so it spent alot of time between 700 and 6200 rpm in all kinds od driving conditions running 23psi of boost.

Interesting quote about volume half way down.
http://www.enginebuildermag.com/Article/...ology.aspx

This discussion got me curious. I spent some time with google and looked at some other forums, Basically there is a lot of varying theories held by participants.

What I found interesting is two video presentations on the Melling site. The 2 videos are down in the middle of the page. http://www.melling.com/Aftermarket/TechInfoVideos.aspx See "Oil Pump Volume and Pressure Explanation" and "Oil Pressure vs Flow

Relevant to our discussion here are relief valve spring pressure and bearing clearances. Both are discussed in the videos.

The engine will accept a greater volume of oil then the stock pump puts out

I'm not sure exactly what you are saying. As worded, I feel that statement is misleading. To me it is saying that the stock pump can never pump enough oil to build resistance to flow (ie oil pressure) in the oiling system. If that isn't the correct interpretation, would you clarify it.

That's not what I was trying to say. But I guess I can see that interprtation. The stock pump will supply sufficient volume and pressure. But the engine will accept a larger volume over and above what the stock pump puts out. What I was trying to say is, the engine isn't "fixed" at "X" amount of oil and that's it. You can pump more oil or a higher volume of oil through it. Which is what the high volume pump does.

My interpertation of the a high volume pump and the attached links is that the engine oil system pretty much has a fixed back pressure created by the bearing clearances, valve train, etc. It will change slightly with RPM, oil pressure, oil temp, oil viscosity, etc. The oil system can accept a high volume/amount of oil, however the pump will be pumping the higher volume against that pretty much fixed back pressure. When this happens, oil pressure will increase. If it increases to greater than the relief valve trip, the relief valve will bleed off pressure.

I think we are basically saying the same thing....just talking past each other.

Volume and pressure are related, for a given restriction flowing more volume will require a higher pressure.
As far as the aux. shaft gears and distributor/pump gear, a higher viscosity oil or higher pressure/volume pump will increase the stress on the gears, for a given engine.

If your tolerances are loose, a high volume pump may be appropriate.